This proposal describes a series of studies designed to examine a family of issues central to the control of urinary acidification. Using conventional clearance techniques we will evaluate the role of alterations in diet and blood pH as modulaters of urinary acidification. In addition, some of the factors controlling extrarenal buffering will be examined. By studying in vitro acidification using the turtle bladder and in vitro sodium and water transport using the toad bladder we plan to examine some of the mechanisms controlling urinary acidification as well as studying the effect of altered acid-base composition on water transport. In a series of complementary studies we will examine the effect of those maneuvers which alter the function of these membranes on intracellular pH or ATP content. These studies will be performed using the technique of nuclear magnetic resonance. This technique has the great advantage over other techniques designed to measure these variables in that it can be applied sequentially in living membranes under experimental conditions similar to those in which the transport characteristics of these membranes are observed.